Si-based amorphous semiconductors occupy the majority of the market presently due to the excellent workability thereof. For example, there is used an Si-based amorphous semiconductor frequently for a TFT (Thin Film Transistor) of a liquid crystal display or for a solar cell.
On the other hand, it is expected for the organic semiconductor to be applied to a wearable device because of such characteristics referred to as lightweight and flexibility. However, with respect mainly to the semiconductor portion, crystal or doped polymer is the mainstream and even when taking a consideration globally, the current situation is in that the development of organic semiconductors such as an organic amorphous semiconductor and the like are remarkably delayed.
Also, there are presently promoted developments of an organic thin film solar cell and an organic EL (Organic Electro-Luminescence) device, which use a low molecule it compound and a photoconductivity-doped polymer, but it is well known that the performances thereof are worse compared with that of an inorganic Si-based amorphous solid. This is related to a fact that high performance or stability cannot be maintained in the processing mode of a thin film, a chip or the like. Similarly as the inorganic Si-based amorphous which has high performance without relying upon the processing mode, it is expected for the organic compound of an organic amorphous solid or the like to have a high potential from an industrial viewpoint, but there are very few examples up to now in which it was applied. That is because the devices known as organic amorphous solids are limited to similar it electronic system starburst molecule groups in which there exist devices expressing conductivity on the radical bodies thereof, but the value thereof is generally very low.
Further, a general organic conductor of a charge transfer type is produced by an electrolysis method or the like, so that it is difficult to control molecular arrangement. Also, the electronic material property is largely dependent on the crystal structure, so that there is difficulty also in a viewpoint of the application to the thin film by polymerization and liquid crystallization which are needed for industrialization.
Also, for the conductive polymer which is made to be a semiconductor by executing a doping, it is difficult to control the arrangement thereof, so that it is difficult for the charge separation capability to be improved. Also, it lacks in chemical stability and the time degradation thereof is terrific.
InSc and GaAs crystals which have high Hall effect are rare metals and therefore, they are expensive and also lack in workability. Lightweight forming or thin-film forming is difficult also for a cobalt oxide crystal which is known as a thermoelectronic material.
Patent Document 1: Japanese unexamined patent publication No. 2005-112951
Patent Document 2: Japanese unexamined PCT patent publication No. 2007-526640